Starter failed suddenly - relay? starter? switch?

[captaincrunch]

1996/6.5/1500 GMC Sierra

Drove the truck several places today. Started 7 different times, no problems. On the 8th attempt . . . nothing. No click, nothing.

Batteries tested 12+ volts. I was unable to do much as I was with limited tools and in a business parking lot. Going back tomorrow to "try harder"

Can starters suddenly quit working like this? I did clean battery connections, but it didn't help. I will check (-) connections tomorrow.

I read something about a "relay" somewhere, and Haynes & Chiltons say somehting about a "fuseable link". Do diesels have one, if so where?

[CoyleJR]

captaincrunch,

Hit the starter case with a hammer while someone else attempts to start it. Often a worn out starter will stick and a love tap with a hammer will get you a few last starts.

Good Luck
John

[captaincrunch]

Had intended to try to fix my truck this morning. But at 39* and a 12 mph wind, well . . . . I may be dumb, but I'm not stupid.

I called a wrecker and went to meet him there. Just for the heck of it I tried to crank it and wohala!, it cranked. So, I drove it home, parked it, shut it off . . . and yes, tried to crank it again . . . . and nothing . . . no click, nothing.

This indicates that when something is hot it isn't connecting properly and when it's cold it is making contact.

Now this question: Is that most likely inside the starter/silenoid, or could it be just a poor cable or wire connection?

[captaincrunch]

Again, it cranked perfect this morning (25* outside!) and again at noon (49*). I replaced all the battery bolts, cleaned all contacts. I did have one battery bolt that was stripped and wouldn't tighten up.

So, then I drove it for a while and, well ... yep.. no crank after.

This has got to be inside the starter. Something is getting hot and separating enough to break current.

Any suggestions as to the best starter? Does it matter?

[DmaxMaverick]

If it doesn't "click" when you try to start, the problem isn't likely the starter, itself. If it were the starter motor, you'd at least hear the high-load relay (solenoid) engaging. When it is failing to crank, check for voltage at the relay coil input while the key is turned to start. If you get no voltage, the problem is with the ign. switch, harness, connector or ign-starter relay (small relay, if it has one, in the underhood power distribution). To eliminate the starter and solenoid as the cause, you can use a remote start switch (old school), which is nothing more than a momentary switch connecting the [large] Batt+ lug to the [small] S lug on the starter solenoid, through the switch. Pressing the button causes it to engage, regardless of the key position. You can buy the tool/switch for this purpose, or make one. It's 2/paired 14awg (or larger) wires with alligator clips at one end, and a momentary switch at the other. The nice store-bought "tool" is a "bulb" type fixture, with a button at one end and the wires at the other, like a joy-stick button. The design doesn't matter, as long as the function is the same. You can also use a screwdriver or other metal tool (old school + shade tree), to connect the [large] Batt+ lug to the S lug, and the starter should crank. If it arcs and doesn't crank, the solenoid/starter is the problem, and if it does nothing, the solenoid is the problem. More info on that, as you need it. Otherwise, start at one end or the other, checking as you follow the circuit.

For the battery terminal bolts, consider the "Swanger" method of correction. It's stainless steel bolts (or studs), with nuts/washers. You can also use brass or cadmium-treated, but SS is most commonly available. They are coarse 3/8" thread. Install the bolt/stud until bottomed out snug (not too tight, just enough to secure it), and use the nut to bear down on the cable end. You'll be able to get a LOT more tension on the terminals than you can using the original design bolts (and they won't strip on you).

[DmaxMaverick]

Also, don't eliminate the ign. switch, just because it happens once warmed up. As you said, it's 25-49° when it's happening, so you're probably using the heater. The ign. switch is probably getting warm, too.

[captaincrunch]

I don't think I've ever replaced the starter on this thing. Boy, can't GMC make a product that would last! I mean, it's only been 17 years.

[Robyn]

Just an FYI here.

The solenoid on the diesel starters draw a lot of current to pull them in and hold them.

The wire used is small and the contact in the IGN switch is small too, and this can and does cause the solenoids to either, not pull in, or to not pull in hard enough to keep the heavy internal connections to the motor touching, resulting in arcing and then failure.

The results are a very heavy amp draw by the motor (way above nomal)
that ultimately causes the motor to fail.

THE FIX

Replace the starter with a new one or a quality rebuilt.

Be sure your IGN switch is in good order as well.

Now, after the years and time on the rigs clock, the wires, splices and connections can and likely have seen an increase in resistance that hampers current flow.

Install a Ford Starter Relay out on the inner fender in a handy spot.
Connect the original small wire that controlled the starter solenoid to run the new relay. ( splice in an extention to suit the need)
Now connect one heavy terminal from your new relay to the battery + using a #10 wire, then connect the other heavy terminal of the relay to the starter solenoid small terminal using a #10 wire.

Tidy up the wire runs to keep them away from sharp or hot things.

This arrangement will take all the heavy load off the IGN switch and the small related wiring and provide the starter solenoid with a good current supply.

This mod is quick, cheap and easy to do and will eliminate starter solenoid issues as you describe, especially in severe weather conditions.

This type of starter issue is not all that uncommon and generally the starter or solenoid gets the blame, when actually the small wire coming from the IGN switch and the resultant lack of current flow is the issue.

I have rewired several 6.5 rigs this way and the results are very nice.


Good luck

Missy

[captaincrunch]

OK, so I finally got around to working on it. I pulled the flap under the wheel well and shorted the solenioid post (purple) to the power post (red) and got a spark, that's all.

That told me it was the solenoid. So, I replaced the starter.

Haven't had time to drive it anywhere to get it hot and see if it will crank. But I'm pretty sure that fixed it.

Thanks for all the input, and if I get time I will do the Ford relay modification.